With 2 strands of yarn held together, cast on

I’m trying to follow a pattern and the instructions say that to start with I have to do the following:

With 2 strands of yarn held together, cast on 24 stitches.
Work set up row on chart on Wrong Side.

Does anyone know how to do this cast on? I tried to look at the cast on techniques on line but I’m not sure which one I should use.

Does any one know?

Welcome to Knitting Help!
Hold two strands of yarn together as if they’re one strand and cast on 24sts by your favorite cast on method (you’ll have 48 loops of yarn on the needle). Every time you work a stitch, you’ll be working two strands of yarn. Just watch your stitches to make sure you aren’t knitting a single strand for some stitches and you’ll be fine. Can you post a link to the pattern or give us a pattern name?

You don’t do the CO any differently than you normally would. You just hold two strands of yarn together (side by side) as if they were one strand of yarn. In the end each CO st will have two loops (two strands) but they count as only one stitch. So when you work the first row you need to be sure and knit/purl both strands of yarn each time you work a stitch.

There’s no difference in the CO – or anything else, actually. Once they’re cast on, you’ll see two strands in each stitch, but they’ll segregate themselves into pairs that you can just treat as one stitch. The only ting you have to watch out for is making sure that you’re working [I]both[/I] strands together. Where that’s been bothersome for me is:
Increases and decreases – especially k2togs.
Leaving a strand “behind” when wrapping the yarn for a stitch. This isn’t catastrophic, but it’ll leave a loop hanging loose that you won’t know where it came from when you get back to it on the other side.
Occasionally, leaving a strand behind on a stitch, which shows up on the next row as an “extra” strand. Sometimes (if you can figure out which one is the “extra” one) you can simply pass it over and it’ll go where it belongs. If I can’t figure out which one is supposed to be passed over, I usually just knit it together with the current stitch and horse on.
If you knit each strand in a pair individually you’ll increase by a stitch. I’ve done this on purpose before because it makes an increase that’s virtually undetectable. But if you’re NOT doing it on purpose, that means you’ll have no idea where the “mystery stitch” came from.

You’ll see all of this better once you’ve cast on. I’ve done as many as 5 strands at a time and even with my experience level it wasn’t as scary as it sounds.