There is more than one choice when considering baseboard construction, which fall into two basic categories a) build your own; b) buy a kit. I have opted for the latter option, because for a beginner not used to carpentry I felt that this was the easiest choice.
The kit that I am using consists of five short (600mm) wooden cross-members and three longer ones (1200mm), which slot together to form the framework, plus a pinboard for the top. Everything is secured together with glue and nails. The instructions supplied with the kit are very comprehensive and easy to follow - (ignore the last instruction as this is for joining several boards together) - and the kit needs a minimum of tools to assemble it - a hammer, a bottle of wood glue, and a woodworkers square or set square. You also need a large flat surface on which to construct the framework - I used the kitchen floor covered with a few sheets of newspaper!
I found it easiest to hammer in the nails part way at the relevant positions around the outer members before starting to glue, and I also turned the framework so that the slots in the long centre-member were uppermost and I could then easily push the short cross-members into the long one, rather than having to lift the structure and trying to match up the slots from underneath.
The short inner members are assembled first by applying glue to the joints and slotting them together. Each member is marked with a black arrow and it is important to make sure that all the arrows are pointing in the same direction when assembling. (This ensures that all the joints line up correctly). When the inner members have been assembled fit the outer members in the same way, securing one side at a time. At regular intervals check the squareness of the frame (using woodworkers square or set square), and adjust it if necessary by pulling gently.
Leave the frame to dry flat for several hours, after which you will find that the frame will have become quite rigid, and it is then ready for the pinboard.
To assemble the top, draw lines on the upper surface of the pinboard corresponding to the cross-members of the framework - to act as guides for the positioning of the nails. Apply glue over the uppermost edges of the framework, and place the pinboard on top. Secure around the edges and along the central cross-members with nails, at approximately 6 inch intervals, and leave the whole structure to dry.
In general the kit was easy to build, but I did find the copper nails included a bit soft to hammer (they kept bending); therefore, I substituted steel ones for securing the pinboard. (Having built the board I found some steel pins at the bottom of the bag which contained nuts and bolts for securing two boards together. I hadn't looked in this bag before because I don't need the nuts and bolts. It pays to check all packaging carefully!)