Hey, i'm new at this crypto issue,i used to invest in the stock market
Welcome

, hopefully you enjoy in here.
and now i want to invest around 10k-15k in few coins (bitcoin,dashcoin,ripple)
how do i start ?
why you choose to invest in dashcoin and ripple? You should learn and find out about these coins potential, not bad at all.
I have no doubt about bitcoin, but do not buy it at the peak, I guess bitcoin price will fall in October. But, if you don't want to miss current rally, you can invest now and sell it if you have certain % of profits.
there are any recommended companies?
Thanks!!
I am not sure there is a company to manage your funds, trade it for you.
But, there are some new projects to invest, if they can make it works, successful, then you may get big portion.
I prefer to trade by myself, choose between coinbase, kraken, bittrex to do it. You can check it this site :
https://bitpicker.io as comparison between exchanges.
Google may help about which exchange is perfect for you.