i am using icloud for my pictures does it mean anybody can look at my pictures that i backup or is it just me

Just in case you aren't already aware, Photo Stream is not a backup. It is a method of allowing you to import your photos to another device. See the following from My Photo Stream FAQ - Apple Support

My Photo Stream uploads your most recent photos (except Live Photos) so you can view and import them to all of your devices. Photos are stored in My Photo Stream for 30 days.

Your photos are safe in iCloud and nobody, but you, have access to them.

They can only look at your pictures if they have your Apple ID/password.

You are welcome.