How do you make a moshling on Moshi Monsters?

You do not 'make' a moshling on Moshi Monsters, you 'attract' a moshling to your garden.

You plant seeds in your Moshling Garden and wait for the seeds to grow into flowers. If you have the correct kinds of seeds and the flowers are the correct color, then you will attract a moshling to your garden. Click on the moshling and you can choose to keep it or set it free.