what is the best way to join my pieces together? and to pick up sts down the sides? i have just finished my sleeves. and my instructions say :
join shoulder seams.
with right side facing, using 3.5 needles K across 8sts left on st holder at left side of back neck, pick up and K16sts down left side of front neck,13sts left on st holderat front of neck and 8 sts left on st holder at right side of back neck. 61sts

What’s the pattern? Join could mean sew the seams in this one - it sounds like it.

it is a baby sweater i have joined the shoulder seams, but cannot for the life of me figure out how i pick the stitches up from the stitch holder so that they are all on my needle?

What kind of stitch holder? It helps if you give us all the info in the first post.

To put the stitches on a needle you just stick your needle through the stitches. If it’s on waste yarn cut the yarn and take it out after the needle is in. If it’s a needle holder you can can pull it out stitch by stitch and put the needle in.

If you’re using straight needles make sure you’re needles tips are facing the right way to knit whatever you need to next.

Yes, from the stitch holder you’re really just slipping the sts onto the left needle, then kniting them. There are some stitch holders where you can use the holder itself as the left needle and knit the sts from the holder onto the right needle.