Curtain header tape

[Decisionsdecisions43]

Hoping someone out there knows more about curtains than me!
I bought these curtains second hand and the header tape has me stumped. There doesn’t seem to be anywhere to attach the hooks.
If the hooks go through the strings then the strings stretch and it looks awful. The same thing happens with the notches the thread passes through.
They are 3m long and very heavy. I’ve attached photos

Depending on the length of your hooks (I’d always use metal and never plastic) You need to put the hooks through a set of loops - I’ve circled options in the attached photo. You can do higher or lower groups depending on the height you want the curtains to sit relative to the pole.
also check if the three sets of strings at each end of the curtains that are used for adjustments of width are tied together before you do this - they should not be coming out like in your second picture

Thanks for replying! The three threads are knotted together. The parts you’ve circled are what’s pulled out in the second photo. Although I only put a metal hook through one set so maybe that’s the issue?
On pencil pleat the loop for hooks have been much sturdier. These are very fine satin thread and stretch really easily

I’ve tried attaching them through the two loops and it stretches out the loops. They’ve been made rather than shop bought and are incredibly heavy!

Photo attached!

the hooks you are using are not really right - they are for pencil pleat heading tape.
what type of header look are you going for?
you could try the ones for pinch pleats like these which go up through all three rows of loops, I use them for all my handmade ones as I’m too lazy to sew proper pinch pleats.