Vivitar TL-125 was popular around Christmas 1988. Good to see your is still going strong!
In terms of ASA ratings, it would depend on whether the model has DX coding (which you would find as a set of gold pins in the bay where you put the film cassette.... If it has, then the asa range would be 50 - 1600 asa. If it hasn't, then Vivitar used to put a small selector on the baseplate of the camera to switch between 100 and 400 asa.
As a rule of thumb, I'd always use 400 asa film in this type of camera.... the extra two stops of speed far outweigh the loss of picture quality - especially with point and shoot zoom lenses.
I can't find a specific manual (no one seems to stockpile them), but if you can read a generic one, try the Vivitar point and shoot here :
(Note, I think you use a different sort of battery, but the controls and placings are all very similar between models).
If you need an original manual, then Oldtimer cameras will sell you an electronic download, or there is an original coming up on eBay in the USA in the next couple of days (with a camera - for spares). If you were really cheeky, you could ask the vendor to scan it in for you.
Hope this helps.