take firs slice

I assume of the cake.

i got the cake and nothing happend

You need to have a wedding cake (with wedding topper to make it a wedding cake), then get married and then your bride/groom should have the option to take the first slice.

How do I get the wessing cake?

how do I get a wedding topper on it, I can't seem to find one (that is the groom by the way it is the same for the bride)

Move the cake to a table and the option should appear.

My sims just got married, and the first slice is all that's left to do, I have a cake and it has the wedding topper but the "take a piece" option is grayed out. it says I have to wait till the newlyweds take the first slice but I'm using the newlyweds. any help os appreciated.

Try moving the cake to a different surface

You need to select the option that is something along the lines of 'cut the cake'