Okay,I once had a topic asking the same question about this.
Once you figure it out,it's not that hard.
Remember,the higher the number,the faster the projectile goes.
So start off with onactivate-self-Spawn Projectile.
The first 3 boxes decide what direction your projectile goes in.
So,for example,putting 100 in the first box would make it go north. Putting -100 in the first box makes it go south.
Put 100 in the second box but NOT The first box will make it go east. putting -100 in the second box will make it go west.
And,putting 100 in the Last box will make it go up. Putting -100 in the last box will make it go down.
Use the last 3 boxes for the Spread of the projectiles.
Putting 25,25,25 in the last 3 boxes will make it have spread.
I hope this helps.