c# using checkbox from form2 in form1

Okay this is a simple question but it's been racking my brain for a while now.

I have two forms.

Form1 Form2

I have some checkboxes on form2 and I'm wanting to use data from checked check boxes on form2 on form1 but when i'm adding the code like follows in form1 it's giving me errors.

if (cbTESTING.Checked) uri_testings += string.Format("{0}.TESTINGS,", word);

obviously I'm getting an error with cbTESTING as it's not referenced on the form1.

so here my question is how can i use / reference checkboxes from form2 in form1?