How can I type اُولٰٓٮِٕكَ on an arabic keyboard. I dont know how to get the ~ (madd) on the laam.?

If you are trying to spell "أولئك" ("they"), then there isn't supposed to be a ~ on the laam in the first place. I think what you are thinking of is how it is spelled in the Quran. In the Quran, there is a small alif in between the laam and hamza, and the ~ is on that small alif, not on the laam. When spelled on a computer, it seems that it is configured incorrectly and both the small alif and the ~ are put on the laam mistakenly. A computer is not designed to type in Classical Arabic, it is only designed for Modern Standard Arabic. There is no small alif in Modern Standard Arabic, nor is there a way to put a ~ on any letter. The only letter that there is a ~ in Modern Standard Arabic is the alif, and it is a key of itself. You put shift+n and you will get آ (alif with madda). However, there is no other letter that a madda can be put on on the keyboard. In Modern Standard Arabic, we never write the small alif. We write أولئك , ذلك، هؤلاء, هذا، هذه all without the small alif.