Hello, I’m Completely New !
When i try to open the main level on start i use Event beginPlay and then Open level and when i do and test it
it bugs and keeps on opening the level two many times like on every frame
Hello and welcome!
Your problem is you are doing the same thing over and over. Instead of opening the level at the start (Begin Play) try going into your Project Settings → Maps & Modes. You can set your default map for editor start or when the game starts. Images below.
Thank’s Man You helped me cause i’m very new to Developing
The answer below should fix your problem nicely. In addition to following @DonBusso recommendations this tutorial series I created for complete beginners may be of use for you moving forward as you begin to explore Unreal.
If you have more questions don’t hesitate to ask, the community is quite friendly. Welcome 
Not a problem. Happy to help.
I am not that advanced myself, just keep playing with stuff it will all start coming together after a while. Don’t give up and if you have any problem or question you can always come and ask for help.
I also encourage you to have a look at the video link @Nebula Games Inc provided. Videos are very informative and pleasant to watch.