A great way to start seeing search results immediately is to use incremental search, and an option is available to highlight matches. This way, everything that matches what you've typed so far is highlighted in the editor window.
To turn on the highlight, from the main menu, click Tools > Options > General, then select the Search tab. Under Additional search options, select Incremental search highlighting.
To start the incremental search, press Ctrl+I (bound to the i_search command in CUA emulation). The SlickEdit command line opens, ready for you to start typing.
Bonus tip: To modify the highlight color, go to Tools > Options > Appearance > Color. The screen elements to modify are I-Search Current Match and I-Search Highlight.