You first need to set a custom search range. To do this press Menu > Search For > Edit Custom > (you can use any of the 10 search ranges, but only custom 1, 2, and 3 have dedicated buttons on the scanner's keypad for quick access). NOTE: The 996XT's 700MHz range starts at 758MHz, entering anything lower will result in an error message.
Once you have set the frequency range (and any other other filters you wish to set), you can use it to search. If you used Custom 1-3 then you can quickly search by pressing HOLD then press 1, 2, or 3. If you used Custom 4-10 then you can search by pressing Menu > Search For > Custom Search (all search ranges will scan by default, you can use the number keys to disable the other search ranges).
You can also set a quick-key for your search range and scan it like any other "system", or enable the "Search with Scan" feature to have it always scan through the search range while in scan mode.
Hope this helps