WORTH NOTING ON TV

* THURSDAY Dateline NBC (NBC, 10-11 p.m.): The bad stuff available to kids via computer goes well beyond sexually explicit pictures and language. According to this edition of the news magazine, it includes do-it-yourself manuals on making explosives, from Molotov cocktails to pipe bombs.

Deborah Roberts explores how easy it is for anyone with a computer and modem - including children - to access bombmaking instructions, and she reports on controversial ideas about censoring computer information. The program looks at what happened to several teenagers as a result, a section some viewers may wish to avoid. * FRIDAY NFL on Fox (Fox, 8 p.m. to conclusion, EDT): Let the games begin - on Fox and not on CBS. And let the real action begin - on the football field and not in the form of media-coverage overkill about Fox's wooing of the National Football League games from CBS for about $1.58 billion.

This contest is between the San Francisco 49ers and the Denver Broncos at the 49ers' Candlestick Park, the first of three preseason games to be carried by Fox before the regular-season games start Sept. 4 on Fox. When these two teams last met, it was also a preseason game, with the 49ers decimating the Broncos, 55 to 10, in Denver's Mile High Stadium.

Fox is making a great deal of this programming coup (note the title ``NFL on Fox''), hoping the addition can move the network into the ranks of the big three - ABC, CBS, and NBC - which typically average much higher ratings. Fox is offering Pat Summerall and John Madden in their 14th season together, with Summerall calling the play-by-pay and Madden the analysis.

A live halftime show features co-hosts Terry Bradshaw and James Brown, as well as analysts Howie Long and Jimmy Johnson. And when the regular-season NFL games start, Fox will use Hollywood reporter Lonnie Lardner to interview celebrities - and oh, yes, some football players - from the Fox football ``Skybox.''

Please check local listings for these programs.