Make my website mobile friendly

I have just had a simple website developed by a freelancer expecting it to be made mobile friendly and have just been informed that she would be charging me more for the privilege - so I require my basic 5 page website to be made mobile friendly.

I will be looking for someone to do it quickly and on the cheap I would be happy to pay around £25 - £30 as a friend told me its easy and she should have done it!

Thanks
Rob