Get onto I-5 North.  Take exit 36.  Stay to the left, following the signs taking you towards Longview/Long Beach.  Stay on this stretch of road for about 2 miles.  It is called Tennant Way.  You will then take a right onto Commerce Ave.  Stay on this road for approximately 1 mile.  You will see the Twin City Painting sign on your right at 1424 Commerce Ave.
 

Directions coming from Seattle:

Get onto I-5 South.  Take exit 36, following the signs taking you towards Longview/Long Beach.  Stay on this stretch of road for about 2 miles.  It is called Tennant Way.  You will then take a right onto Commerce Ave.  Stay on this road for approximately 1 mile.  You will see the Twin City Painting sign on your right at 1424 Commerce Ave.