As a Lithuanian citizen you are able to enter the US without a visa, however you WILL require an approved 'ESTA' before you travel - searching this site will find you several other questions that cover what is required for an ESTA.
However your biggest problem will be your age. As you are below 18, you will require your parents consent to travel internationally and to enter the US - you can find some further details on this on the US CBP website.
However once you arrive, you will need somewhere to stay. Hotels in the US will NOT allow someone below 18 to stay without an adult, so you will likely not be able to find somewhere to stay.
You will also need to consider things like medical insurance, as well as carrying a medical power of attorney in order to give someone the right to decide on any medical treatment that should be needed should you fall sick/have an accident whilst in the US (as you are under 18, you can legally not make these decisions for yourself)
In short, travelling to the US at this stage is likely not a good idea at all - especially given that you appear to have done very little research into what is required.