Praise be to Allah.
The basic principle is that it is not permissible to sign up for these advertising programs unless one can be certain that the sites advertised are sound and are free of haraam things, because it is not permissible to advertise, promote or help to spread evil. Allaah says (interpretation of the meaning):
“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”
And the Prophet (peace and blessings of Allaah be upon him) said: “Whoever calls others to guidance will have a reward like the rewards of those who follow him, without that detracting from their reward in any way. And whoever calls others to misguidance will have a burden of sin like the burden of those who follow him, without that detracting from their burden in any way.” Narrated by Muslim in his Saheeh (4832).
If the matter is as you describe, and most of the ads that will be placed on your site are for teaching languages and the like, then we hope that there will be nothing wrong with you signing up for this program, especially since you need the money.
You have to block the ads that go against shar’i rulings. If you are unable to do that, and these ads appear on your site against your wishes, then you have to leave this service because otherwise you will be a partner in spreading and propagating haraam.
We ask Allaah to provide for you by His bounty and to provide generously for you and your family, and to help you in your absence from home.
And Allaah knows best.