‘Response has been terrific, but we need more participation from Wellington,”’ Skip Merrill, organ izer of the Wellington Art Assn. said today of the group's Jan. 20 31 exhibition here. Merrill said entry forms had been sent in from as far away as Benton, Ark. More than 700 forms were mailed to art enthusiasts throughout the state for the first annual competition. Theme of the show is “A City At Night, and the artists are to de pict their feelings on this subject ion 24-by-24 inches of canvas or canvasboard. Only oil paintings will be accepted. The exhibition is for amateurs only, but work of several profess ional artists is expected to be on display at the 121 South Washing ton location. Association officials urged all persons interested in participating in the exhibition to mail entries to Merrill’s studio at, 615 West Twelfth.