You have two options!! 1. Use a responsive template (Html or WP) -it will work on almost every devices from mobile to mac 2. Build a mobile website with xhtml/css (remember: mobile browsers can't read complex functionality.. so you have to use basic/simple xhtml or php or jquery) Hope these helps
Use wptouch plugin. This is a free (premium also available), plugin and can make your site mobile compatible in just one click. give it a try
I would strongly reccomand Uppsite they convert every WP site to mobile within 2 minutes and submit it to Google play and Appstore.
I am also using wo touch plugin but I did not find many changes ,may be problem with my theme but WP touch is good plugin