Need help with my first project

So I am a beginner. I bought a book with easy knitted blankets and picked a pattern that I kind of got stuck. I searched everywhere, but I still have no idea what I am doing.

Basically the chevron pattern is (multiple of 12 sts+3sts) what exactly does it mean, is that how it goes… 15,27,39,51,63,75,87,99,111,123,135,147? and where do i use these stitches?

Then there is Row 1(RS): K1, ssk, *K4, YO, K1, YO, K4, s2Kp; rep from * to last 12 sts, K4, YO, K1, YO, K4, K2tog, K1.
I read that from the star i need to repeat the pattern. I have tried, but i was left with missing stitches, so i got really confused, i think I am missing on something
I really would like to get this blanket done, I would really appreciate any help from you all!

Thank you for all your time!

Hi and welcome!
A multiple of 12 + 2 is telling you how to increase the size of the pattern in order to make the size blanket you’d like. You’ve got the stitch numbers correctly figured out (15,27,or 39 etc). Somewhere at the pattern beginning will be a stitch gauge telling you how many sts you should have per inch. Using that number you can figure out how many sts to cast on (that is, which of the above numbers comes closest for the size blanket you’d like).
On row 1, yes, repeat the stitch directions between the asterisks. Make sure you’re doing the yarn overs and the ssk, k2tog and s2kp correctly. The yarn over doesn’t use a stitch but occurs between sts. The s2kp is a centered double decrease, like this:

Try this out with a cast on of 27 or 39sts to see if you can get the pattern to work on a smaller scale.

I guess I am still not getting this right…I wanted someone to show me how to do the first row and I would be good to go…
I am more visual person, maybe this is why and my issue is that I keep ending up with more stitches…I have watched the videos, just to make sure I’m doing stitches the right way and I just end up with more stitches and then i get confused.
The first thing i do is I CO 147 sts and then I beg my chevron patt…the first row i do K1, ssk…from the asterisk I do K4, YO, K1, YO, K4, s2Kp and repeat until I end up with 12 stitches?? after I have 12 stitches left do I do K4, YO, K1, YO, K4, K2tog, K1…that is just 7…what do i do with the 5 sts?? That is where i am stuck…

K4, YO, K1, YO, K4, K2tog, K1

You’ll use all 12 sts

k4 uses 4
k1 uses 1
k4 uses 4
k2tog uses 2
k1 uses 1

Make sure you aren’t adding stitches by an extra YO or accidentally picking up the thread in between stitches. Those are common mistakes for new knitters.

Does the blanket have a name? I know you said it’s a book, but a name would help so we can look it up and see what it looks like.