You can browse only topics for themes that you have purchased.
You need to add purchase code to unlock topic for specific theme.
If you have bought more then one theme, then you need to add purchase codes for all of the purchased themes to unlock topics for these themes.
We understand that there is a fine line between what is considered support & modifications. We will try help you with any type of query, but we can't provide extensive help in terms of modifications.
If you're not familar with magento and having troubles with installation, or want to make changes that go beyond our basic support, you can order customization services.