how to use ipad to access webserver on macbook air my webserver software is nginx which runs very well on macbook air using mac os x 10.7.5

when i go to http://myapp.localhost on my macbook air, i can access my website perfectly which is running on localhost.

how can i access the website from my iPad? I am asking because i want to test if my website allows tablet to access just as well on desktop browsers.

i have two possible setups.

1) macbook air running HUAWEI-MOBILEModem and using INTERNET SHARING to allow the iPad to access.

2) when both macbook air and iPad are accessing the same WIFI connection.

Please provide solutions for both scenarios.

UPDATE:
i have more than 1 app running on my macbook air nginx webserver.

for conveniences, let's call them 


http://myapp1.localhost
http://myapp2.localhost


etc.

How can my iPad access the correct webapp hosted on my macbook air?

UPDATE

on my macbook air, i access different webapps because i edited my /etc/hosts file.
localhost is device-specific, so visiting it on your iPad is is taking you to a page on your iPad itself (that probably doesn't exist).

To access a page that is served from your Mac from your iPad, use the Mac's local IP address instead of localhost. To get your Mac's local IP, open the Network pane of System Preferences. Select your active network on the left and the IP will be shown on the right under the Connected heading. It will probably be something that looks like 10.0.1.1 or 127.0.1.1.