The H23 is a trailer boat. It is designed to be easy to raise and lower the mast.
If you follow the link in Steve's post you will see a pole attached at the base of the mast to act as a lever. That is the gin pole. It is specific to small trailer boats that need to raise and lower their mast each time they go sailing. A quick Google search on H23 mast raising will find specific instructions.
While the gin pole makes things much easier, the mast on the H23 can be raised or lowered without it.
The main steps are as follows (safety tips skipped):
1. Remove both sails and the boom.
2. Connect a halyard to a block and tackle anchored on the bow. The gin pole would go here. The main sheet is usually used as the block and tackle.
3. Connect the cables that keep the mast centered. (most likely missing with the gin pole.)
4. Disconnect the forestay and lower the mast aft by letting out on the block and tackle.
5. Pull the pin at the mast step and walk the mast forward to center it on the boat.
6. Secure all the rigging. Every owner has their own tricks and tips for this part. I use the halyards to tie all the cables to the mast.