im a newbie so excuse if these are stupid questions.
ive got frame that i want to convert but dont im unsure on what size parts i need for this frame. eg. how do i measure the size of the headset? same goes for the seatpost etc.
Is there a link someone can give me so i can get the right parts for this bike?

Buy a vernier caliper.

If you post pictures of the frame here you’ll probably get some answers.

yeah ok. thanks
how do i know what size headset fits my bike tho? where do you measure to and from?

inside diameter…

it is most likely 1 1/8" or 2.8575 cm for those not stuck in the 17th century if it is indeed a ‘conversion’ like you said.
although, we all know it is unsafe to assume what people tell you on the internet to be the 100% truth.

have you got any information on the frame ?

Yer, you can measure the inside diameter with a ruler which will give you a close enough measurement to standard sizes. A caliper, however, will give you more precision (obviously). Google ‘Sheldon Brown’ and you’ll find plenty of info to get you by.