raspberries post and wire system

Hi, have planted some raspberry canes and have two posts in the ground on either side of the row. Now need to set up the wires:

what sort of wire should I use and whats the easiest way to fix it to the posts?

Thanks!

Classic single fence system, stretch wire between posts at two and half foot, three and a half foot and five and a half foot up from the ground. Brace the two end posts or they will get pulled in when the wires are tightened.
 

NB you didn't say, I assumed the posts are wood, if metal you would need straining bolts rather than vine eyes.

ive put my posts in the weekend and was thinking of using a washing line ,,,not wired up yet so anything can happen