if/else statement using <cond>

so im using the idm plugin for netbeans and when i drag the if input to the screen it gives me a format like this:

<cond>
<!-- if -->
<!-- then -->
<!-- else -->
</cond>

but this doesn't work when i fill it out like that. in the if statement, i need to reference a field i have declared before, so i do that like this:

<if>
<notnull>
<ref>variable</ref>
</notnull>
</if>

but it gives me errors that <if> isnt filled out correctly. what do i do?