how to activate ssl certificate for my website

It is written that SSL certificate will activate by default, but when I enter my website it show ‘not secure’ in HTTP field, should I have to activate SSL certificate manually if so then how can I do that, guide me over these

Under SSL by default they mean self-signed certificate. To get green lock on your https page use cloudflare. You can enable it in your vPanel, read more about it at knowledge base.

thank you Mrjunior

does altering cloudfare change my DNS settings which in result affect my domain ?

If you’re enabling CF with vPanel - your DNS still being managed by InfinityFree system and site wouldn’t be affected, If you do it manually, by changing nameservers by yourself, you’ll be responsible for DNS in CF DNS section

I enabled cloud fare yesterday but still, there is no blue tick in http field

What is blue tick? If you mean green lock(l0l) - you gotta to configure your ssl and other cloudflare stuff from their client area, more information here: