Tony,
Though you didn't say what device and software you have, I'll assume you have an iPad with the latest version of Pages installed;
The latest version of Pages moved the tab button that used to be on the tool bar to a submenu that you access by:
1. Tap once in your text to make an insertion point
2. Tap the insertion point one more time and you should see a menu above it that says "Select | Select All | Paste | Insert"
3. Tap on the word "Insert" and you will be presented with a menu of options. The top option is "Tab" - if you tap the word Tab a tab will then be inserted into your text
4. This will also work in text contained in a text box - getting the initial insertion point to be inserted takes practice, but once you have an insertion point, tapping it once will open a menu (less options for text boxes) where the first option is "Tab" - tap the word Tab and a tab is inserted.
I'm guessing you are having trouble getting the initial insertion point. It takes a light touch, a bit of patience and a little practice, but it does work. You will get there eventually.