Will start long term investment at the end of this month, any guides, suggestions etc.?

Basically the title. Some background info: 1- collected 10k euros in Cash, as emergency fund 2- i will now be able to invest money into things but i am super super newb. 3- I live in Germany I have revolut account, and some fun bullshit stocks i bought which is worth 400 euros. 1- should i buy stocks from revolut? Or another app? 2- i keep hearing etfs for long term investment, which etfs do I buy? These will be my looooong term investment, like maybe cash in after 10 years to buy a house type o