I am going to do it!

Hi everyone ;o)
Firt time posting here, just foundt out that this forum existed a few days ago.
After looking (veeeery jealously) at all the beautiful art you all have made, I have gathered enough
courage to make a birdbath (mould from leaves).

Have some questions, do I use regular cement, and what is concrete sealer?
Not sure if I can find it here, never looked for it before, is there something else you can use?
Monica ;o)