Welcome to the forum!
1 -- Enable the Pen/Bezier tool
2 -- Click once to start a new path and set the first node
3 -- Move the mouse over
4 -- Click once to set the next node
5 -- Move the mouse over again
6 -- Click once to set the 3rd node
7 -- Move the mouse back to where you started.
8 -- See the tiny square at the beginning of the path? Place the mouse inside that tiny square
9 -- Click once to end the path
10 -- Now the path will turn black and you should see a triangle (at least that's what it looks like you mean by "pointy shape")