The red and yellow tables in the foreground are mixed in among the forward facing cars. They are not the picnic tables. You can ask to be seated at one when you check in, but the castmember may say they are designed for parties that include a wheelchair or for larger groups. These particular cars have two 4 tops so if you are a smaller group expect another group to be seated next to you.
The picnic tables are visible in the picture. They are way in the back behind the CM and under the two rectangular wall pictures. They are small, but we've seen groups of 4 seated at them. You can also see the seats which are backless stools. Walkups are frequently seated at the picnic tables.