Hi Omar and welcome.
As an introduction to cycling be aware of the first golden rule: no matter how much kit you have it is never enough!
Best thing to do is to look at how far you think you will be riding to start with and where because this may help deciding what yon should have now and what you can build up to over time.
I'd agree that a helmet and glasses are important but that is a personal choice, if you think the same then fine.
P***ture repair kit and or a spare inner tube and then tyre levers and a pump.
Other tools: I used to carry just a couple of allen keys. This in part was because I was no good with a tool kit and in part because I wasnever more than a couple of miles from a main road/village/bus/train route.
Gloves/mitts i started without but soon found that this was uncomfortable and bought a cheap pair from my LBS.. Others I know are fine with nothing.
Drinking bottle/hydration systen. If you set off doing 30/40 miles and are not in the middle of nowhere then one cage and one bottle should suffice, worst case you stop and buy a drink along the way.
Clothing: Here's another can of worms. You can cycle in ANYTHING. the difference in what you wear will be your degree of comfort, warmth coolness, drynes etc depending on what you are wearing. This is in part a function of your preferences, some people heat upquickly some don't mind getting wet as long as they stay warm etc, and is a function of how long you are out for.
When I started I got some padded shorts, this made a big difference to having ridden around town in jeans. I then aquired a couple of short sleeve cycling tops. If you are out for an hour or so to start with you may be comfortable enough in a t-shirt (but then you'll need a saddle pouch for the repair kit/inner tube). If its a bit colder then tracksuit bottoms over the shorts and a tracksuit top/sweatshirt over the top will probably do to start with.
lets hope that summer is comming so the need for raingear, mudguards, cold weater tops, gloves armwarmers legwarmers etc is less pressing than it will be later in the year. But that's why Christmas is in December!
If after a couple of months the bug has well and truly bitten, you can look to start getting more gear as you decide you need it on the basis of YOUR experience.
One final tip, work out the budget for kit, ask on here and look around see the price of different items and read the reviews, I have a 20 quid Specialised helmet which does everything I need for what I want, it got good reviews and is from a good firm.
Sorry, this IS the final tip! get out there and have fun on your bike.