Cick the "Search" button at the top of the forum (fourth from the left). Type in the members name you want to see the posts from in the "Search By User Name" box (right side, top section). Click "Perform search".
Click the profile button of the member in a post they have made. In the colored bar across the upper area, where is says "Profile for (whoever)" on the left, click the "Search for all posts by this user" link on the right.
Hope that answers your question.
My Rig: SABLE
Antec 300 Illusion / Antec EarthWatts EA650 650W / EVGA GTX 760 2GB
AMD FX 8320 x8 Black Edition / Gelid Tranquillo / MSI 970A-G43
Sandisk Ultra Plus 128GB / Samsung 840 120GB / WD Black 750GB / WD Green 1TB / WD Red 3TB
G.SKILL Ripjaws 2x2GB DDR3 1600 - Crucial Ballistix Tracer 2x2GB DDR3 1600
Win7 Ult 64-bit - Func MS3 Mouse - CM Storm QuickFire Rapid Mech Keyboard
R.I.P. Danny L. Trotter
... 14 Nov 1945 - 4 Sept 2009