I love reading but I have never done any constructive critiques before, it's my first time so is there any thing to critique for beginners? It's a huge jump.
Me neither, despite the "Reviewer' banner. I intend to just jump right in any day now. I assume if I get the critiquing thing wrong, folks here will let me know.
If you want, you can take a look at some of the other critiques in the Workshop to get a feel for how to critique. That should give you some ideas on where to start, what to look for, etc. After that, just jump right in and start critiquing.
You could start with something short like flash fiction. It's easier to penetrate than most poetry or evensong lyrics, and the brevity makes it a bit less intimidating.
Most writers are just looking for an honest reaction to what they've written. If you can say what you like or don't like about the piece you choose, that will be very helpful. You don't actually need to offer advice to 'fix' it, if you don't feel confident doing that. Just pick a Workshop entry that stirs a reaction in you, and go for it. You'll do fine, I'm sure.
If you're looking to write anything fantastical, whether it's sci-fi, fantasy, horror, or whatever, the best one-sentence bit of advice ever given has to be Michael Moorcock's observation that the one absolutely inescapable difference between good and bad fantasy is that the good stuff is always internally consistent. By which he means that if you think that you as the author, and therefore God, can make it up as you go along, it'll be a mess. But if you assume that your role as author/God is to invent your own rules and make your characters stick to them, it'll work a whole lot better.
The mere fact that you asked the original question makes me think you'll be a good reviewer. You will think about what you say, and will try to do a good, constructive job.
You start with whatever you already know, which often is just the reaction of a reader, an important thing not to be underrated. As you learn more you'll start to notice more: is there interesting conflict do you like or hate a character would you keep reading
I'm a beginner as well, but I've found it's easy to pick up on mistakes like tense slips or point of view changes in other people's work. Or for basic readability. Can I understand who's talking at that precise moment? Etc. Soemtimes people miss these little things that another eye can spot, no matter how inexperienced the one critiquing. I've also been reading a lot about how to write better. It's made me a far better critic. You might pick a book from your local library. Or through your electronic library, if you have one.
It is easier to spot weakness in the writings of others because you are able to look at it more objectively. And critiquing others really does help you improve your own writing. A win-win situation They say it is much easier to recognize great writing than it is to write it. So, even newbie writers can offer some insight to fellow writers...what works, what doesn't. We all come to the table with different experiences, different strengths, and different weaknesses, and by sharing, we only make one another stronger.