Please help about responsive site

Hello,
this is my first post in wordpress forum. I am in big problem about my site. I use free wordpress theme. I need to make it responsive. In my adsene suggestion it shows my site is not mobile friendly. Can you please suggest me how I can make my site mobile friendly, any plugin to make it responsive or mobile friendly. I hope someone will help me.
thanks in advance.

See original post by tanvirbd