how do you find a history of someones postings

Search their TER id on each individual board using the search feature. You can set the timeframe any way you want, although the default setting is 30 days. Usually you'll want to search farther back than that – six months or a year.

Just to add to what bbbmmm22 stated:

1. Click on the Board that you want to search (ie. General Discussion, FAQ for Newbies, etc.)

2. Just under the top of the Board page, there are four green-ish boxes "top 10...", "search messages", "post message", and "overview".

3. Click on the "search messages"

4. Fill in the 'author' blank with the member's name.

5. Change the date fields to match whatever timeframe you are interested in.