I don't see any reason you can't upgrade from the version pre-installed by webhostforasp, though I'm not sure how new/old the version they install is. To find out your current version visit the (Key icon) Administration Menu > System Information, unless its a really old version it should show you what version of mojoPortal you are using.

For any upgrade you should back up your site and your database so you can restore it if anything goes wrong. You will definitely need to backup your Web.config file so you can get any custom settings like your conection string etc and enter them in the new Web.config.

So basic steps are:

backup everything

replace files with new files using ftp (I usually upload the /Setup folder first then ClientScript, Data, then everything else. Breaking it up a little helps prevent timeouts during upload.

edit the new Web.config to restore your connection string and any other custom settings like smtp.

visit /Setup/Default.aspx and it should run the upgrade scripts

Hope it helps,

Joe