Hi Helena.
Not sure if you speak any Spanish, or if they speak any English! But here are two tel.no's for horseriding in or near Salou:
Hipica Divertipark: +34 977 365552 which is in Vila Fortuny
or
Hipica Mont.roig
+34 650 499610
which is a bit further out, but they have some beautiful Spanish horses, and arrange treks through the local countryside, which is also beautiful.
I understand that there are some brochures about horse riding in most hotels as well.
