diff --git a/init.sql b/init.sql
index 14c4e7f..abb228b 100644
--- a/init.sql
+++ b/init.sql
@@ -34,3 +34,4 @@ CREATE TABLE orders(
     price BIGINT NOT NULL,
     order_id UUID REFERENCES orders(id)
 );
+ALTER TABLE orders ADD CONSTRAINT order_price CHECK(price > 0 AND price < 100);
diff --git a/pages/market.html b/pages/market.html
index 927cbf8..d5333bc 100644
--- a/pages/market.html
+++ b/pages/market.html
@@ -80,10 +80,10 @@
                     {{ else }}
                     <td></td>
                     {{ end }}
-                    {{ if and (eq .ShareId $.YesShare.Id) (eq .Side "BUY") }}
+                    {{ if and (eq .ShareId $.NoShare.Id) (eq .Side "BUY") }}
                     <td>
                         <div class="flex yes">
-                            <span class="align-left">YES</span>
+                            <span class="align-left">NO</span>
                             <span style="width: 100%" class="align-right">{{.Quantity}} @ {{.Price}}</span>
                         </div>
                     </td>
@@ -97,7 +97,7 @@
         <hr />
         <details open class="align-left">
             <summary><span class="font-mono mb-1"><strong>Order Form</strong></span></summary>
-            <form id="form" class="order-form" hidden action="/api/market/{{$.Id}}/order" method="post">
+            <form id="form" class="order-form" hidden action="/market/{{$.Id}}/order" method="post">
                 <button id="buy" type="button" class="order-button yes w-100p selected">BUY</button>
                 <button id="sell" type="button" class="order-button no w-100p">SELL</button>
                 <input id="market-id" hidden name="market_id" value="{{$.Id}}" />
diff --git a/public/400.html b/public/400.html
new file mode 100644
index 0000000..b7ada56
--- /dev/null
+++ b/public/400.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <title>delphi.market</title>
+  <link rel="icon" type="image/x-icon" href="/favicon.ico" />
+  <link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png" />
+  <link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png" />
+  <link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png" />
+  <link rel="manifest" href="/site.webmanifest" />
+  <link rel="stylesheet" href="/index.css" />
+  <meta name="viewport" content="width=device-width, initial-scale=1" />
+  <meta name="theme-color" content="#091833" />
+</head>
+
+<body>
+  <header class="flex flex-row text-center justify-center pt-1">
+    <nav>
+      <a href="/">home</a>
+    </nav>
+  </header>
+  <div class="container flex flex-column text-center">
+    <code>
+        <strong>
+          <pre>
+ _  _    ___   ___  
+| || |  / _ \ / _ \ 
+| || |_| | | | | | |
+|__   _| |_| | |_| |
+   |_|  \___/ \___/ </pre>
+        </strong>
+      </code>
+    <div class="font-mono mb-1">Bad Request</div>
+  </div>
+</body>
+
+</html>
\ No newline at end of file
diff --git a/src/db.go b/src/db.go
index 9b03fd0..4dce1c8 100644
--- a/src/db.go
+++ b/src/db.go
@@ -84,3 +84,12 @@ func (db *DB) FetchOrders(marketId int, orders *[]Order) error {
 	}
 	return nil
 }
+
+func (db *DB) CreateOrder(order *Order) error {
+	if _, err := db.Exec(""+
+		"INSERT INTO orders(share_id, pubkey, side, quantity, price) "+
+		"VALUES ($1, $2, $3, $4, $5)", order.ShareId, order.Pubkey, order.Side, order.Quantity, order.Price); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/src/market.go b/src/market.go
index 42d63a7..31a2cbb 100644
--- a/src/market.go
+++ b/src/market.go
@@ -2,10 +2,10 @@ package main
 
 import (
 	"database/sql"
-	"log"
 	"math"
 	"net/http"
 	"strconv"
+	"strings"
 
 	"github.com/labstack/echo/v4"
 )
@@ -25,10 +25,10 @@ type Share struct {
 type Order struct {
 	Session
 	Id       string
-	ShareId  string
-	Side     string
-	Price    int
-	Quantity int
+	ShareId  string `form:"share_id"`
+	Side     string `form:"side"`
+	Price    int    `form:"price"`
+	Quantity int    `form:"quantity"`
 	OrderId  string
 }
 
@@ -48,8 +48,27 @@ func BinaryLMSR(invariant int, funding int, q1 int, q2 int, dq1 int) float64 {
 }
 
 func order(c echo.Context) error {
-	// TODO: implement POST /market/:id/order
-	return echo.NewHTTPError(http.StatusMethodNotAllowed, "Method Not Allowed")
+	// (TBD) Step 0: If SELL order, check share balance of users
+	// (TBD) Step 1: respond with HODL invoice
+	// ...
+	// Step 2: After payment, create order if no matching order was found
+	o := new(Order)
+	if err := c.Bind(o); err != nil {
+		return echo.NewHTTPError(http.StatusBadRequest, "bad request")
+	}
+	session := c.Get("session").(Session)
+	o.Pubkey = session.Pubkey
+	if err := db.CreateOrder(o); err != nil {
+		if strings.Contains(err.Error(), "violates check constraint") {
+			return echo.NewHTTPError(http.StatusBadRequest, "Bad Request")
+		}
+		return err
+	}
+	// (TBD) Step 3:
+	//    Settle hodl invoice when matching order was found
+	//    else cancel hodl invoice if expired
+	// ...
+	return market(c)
 }
 
 func market(c echo.Context) error {
