First thing you have to keep in mind that installing a new template is an enormous mod to your board : count the file purely replaced to convince you
. So some templates, very close to subSilver will be really easy to modify, some which has broken with the subSilver structure will just be a nightmare, and will require a good understanding of how a tpl file is written.
A tip to ease the job : as there is no need to have a template on admin side, just use the subSilver admin files in replacement of your admin dir (templates/your template
/admin) : this divide the job radicaly, also for other mods.
Then in categories hierarchy, we deal more with using a new tpl file than editing an existing one. Most of the modification (ie in index_body.tpl) consists in removing the categories and forums box, as the mod will use in place the new tpl file (index_box.tpl). By simply setting the class of your template in replacement of the one used by subSilver (cat, gen, row1, forumline, etc.) in index_box.tpl, you should get the expected result, or be very near of it
. The reason of creating this new tpl file was simply to avoid a long and harsh editing of the index_body.tpl, and the duplication of this in viewforum_body.tpl, as forums and categories can also be displayed in this view
To help you, the modified files pack included the result of an installation on subSilver template, to compare with your installation. By seeing the subSilver file before and after, you should be able to recognize the modification more easely than only reading the install description (which will only point some spot).
Hope this will help