if a client of mine was on a talk show but the exact show isn't listed on imdb, just the show in general and some of the episodes, can i just list the show he was on with the amount of appearances and the year? I don't know the name of the paticular episode.
No. You'd have to click "edit page" and add to the cast of that episode. If it's not yet listed, you'd have to, first, add the episode. If you don't know the name of the episode, do you know the date? You can search by the date to find it, if it's listed. If you click on the show's season you should get a list of episodes with dates in the upper right hand corner of each.
Mark: You can submit an episode to IMDb if you know the original airdate, even if you don't know the episode title or episode number. Just go to the page for the TV series and click "Add episode". Then, on the next screen, submit the original airdate (and the country to which that airdate applies). You can leave the episode title and number blank if they are unknown. Also, indicate your involvement in the "I am ..." dropdown box. Then click "Check these updates".
On the following screen, you will be able to start the process of submitting the cast who appeared in that episode. The process should be largely self-explanatory from there.