You could start by making or drawing the first row. Try to be aware of how you are making/drawing the triangle.

Now add the second row. Again, try to focus on how you are making/drawing this second row of triangles. Might your way of drawing/making help you see why that number of sticks/lines is needed?

How are you going to keep track of the number of rows you have made, the number of small triangles you have created and the total number of sticks/lines you have used?