New knitter with guage?

When the pattern I have chosen to try (cloverleaf) just gives the multiple (8 sts.+7 How do I determine how many stitches to cast on to do a swatch. If I find a pattern stitch I like well enough to make a baby afgan out of How do I determine the number of stitches to cast on for a certain size baby afgan say a 36 by 36’ Please describe in easy beginner terms I have not done any thing but knit and purl so far.

When a pattern gives you a number like 8 + 7, your pattern will need any multiple of 8, plus 7 more. So 16 + 7, 24 +7, 32 +7.

To make a specific size, do a swatch, determine how many stitches per inch you’re getting and multiply that by the number of inches you want to make.