I would say what I have normally replied to them with on other threads in which they said they were interested in Islam - to read up on the five pillars of Islam and the six articles of faith. If they learn those and study them carefully, then they will become that much closer to realizing if they are capable to being Muslim or not from their hearts. There is a very good reason why we have these five pillars and six articles.
I don't know what words from the Qur'an I would use. It depends on what they want to know about Islam. Every person is different. I would tell them to read the whole Qur'an, otherwise they may not fully benefit from it as they should. As for websites, I would not encourage that at first. Websites can be misleading. If they go to the wrong website, then they may fall into the wrong line of thinking and reject the Islamic beliefs and go astray. So that would be a dangerous road. No websites at the very beginning. Too risky.