--I'm told radicals combine with each other and other characters to make words
No, radicals are one component of Chinese characters. They do not combine with each other to make words. They do not combine with other characters to make words.
Not all components of characters are radicals. What you wrote is correct: "it just helps you find the stroke category in a dictionary". If you are looking up the character 枫 (maple), for instance, the radical is 木 (wood, tree). The other part, 风, is not a radical, at least not in this word. 木, the radical, helps you look up 枫 in the dictionary. 风 indicates the pronunciation (roughly) but is not a radical.
--some radicals denote sound for pronunciation of the word
These aren't very common. Probably the majority of radicals indicate the semantic category of a word, like 木 (wood, tree) in 枫.
There is a fundamental confusion in your question between characters and words. Characters are written forms. Except for very simple characters, they are made up of various written components or elements, some giving a hint of meaning, some indicating pronunciation, and some representing garbled (and misleading) versions of their ancient form.
Characters in Chinese mostly equate to morphemes in linguistics. Words are created by combining morphemes together. For instance, 枫 'maple' and 梨 'pear' are two morphemes (each written with one character) that can combine to form the word 枫梨, meaning 'pineapple'.
Words are NOT created by combining radicals. The word 枫梨 is made up of 枫 and 梨. It was not created by mixing and matching radicals like 木 and 风 and 木 and 利. These four forms all occur in 枫梨, but only as constituent parts of 枫 and 梨, not as constituent parts of the word 枫梨. Radicals, as mentioned above, are components of characters and, as also mentioned above, are just used for indexing characters.