Can anyone help. Finished grandson sweater but stuck on how to put it all together.This is the point at which I cannot continue:Join front raglan seams and right back raglan seam.Neckband: Using 3 1/4mm needles and with right side facing,knit across 7sts of left sleeve top, pick up and k12 sts down left front slope, knit across 9sts at front neck, dpick up and kn12 sts up right frontslope, knit across 7 sts of right sleeve top and 21 sts at back neck inc 1st at centre. 69sts. Starting with a 2nd row work 7 rows in rib as given for back. Cast off. I will have to join yarn on to the first 7 sts to carry on picking all the stitches. I am in a muddle with it but I think its easy if you do it once. Also how do you pick the stitches up on the left slope. Many thanks. Lucy
Finishing Neckband
Is the pattern from a book or online? If it’s a free pattern please post a link to it so it’s easier for us to help.
I’ve not made enough sweaters to help much unfortunately and I usually do seamless, but someone should be along to help you soon. Hang in there! 
I’ve never done a raglan, but it looks like you would sew the front part of the sleeve to the body of the sweater and also the back of the right raglan seam. Then as you said you would attach yarn and begin picking up the required number of stitches on each piece of the sweater. You can use a crochet hook if that’s easier. When you have picked up on your needle all required stitches you would have 69 stitches, work as directed in the pattern for the neckline and bind off. Then you would finish sewing the remaining seams, tuck in loose ends of yarn and done.
They’re having you connect the 3 seams so you can work the collar back and forth. You’ll put the sleeve stitches on the needle, pick up stitches to the right of the center of the neck where your neck decreases were–just space them as evenly as you can, across the front center of the neck and up the left of the neck, the other sleeve and the back of the neck.
Are your questions answered?