Yes you will want filler. There are several available but I like this;
http://www.stewmac.com/Materials_and_Supplies/Finishing_Supplies/Fillers_and_Putties/ColorTone_Waterbase_Grain_Filler.html
You'll want this one. #0220-A
If this is your 1st, and we always remember our 1st, you'll want to...