You'll need 2 for loops. One inside of the other.
The first one should go from 0 to the number of lines.
The second one should go from 0 to the index of the first one.
In the inner loop, print a *
After the inner loop, but within the second loop, print a \n or endl.
Please post some of the code you have tried and we'll go from there :)
All the best,
Nice, that works well--thanks!