Using tube clamps could not be any easier. Each tube clamp is made from galvanised malleable iron that comes complete with a set screw.
Choose the correct tube clamp size depending on the size of tube you are using. e.g. if you are using 48.3mm tube then you will need to use the 48.3mm fittings.
Insert the tube into the fittings and tighten the set screw with an Allen key. It really is that simple.
A common combination of fittings would be a base, a tee, a corner or an elbow, a cross piece and a wall flange if connecting to a wall is needed.