Well to start with, you will have way more than 90 frames in your video..

For example for NTSC region (US, Canada, Japan), you should have 29.97 Frames per Second (fps) of video. 90 frames would give you a 3 sec video, with the 90 photos flashing by so fast that you would not be able to see them...

So one thing you need to do is determine how long you want your video, which will also help determine the duration of each image. You can go into the
Preferences dialog (File>Preferences or just press [F6] on your keyboard), and then go to the
Edit tab, where you can set the Default image/color clip duration. You can also manually adjust the duration after you have dropped your image onto the time-line by grabbing the yellow handle on the right or left side, and dragging it. Then one final method that can be used, after you have inserted all the images, and decided that you want to change the duration of all images, is to multi-select them, then go to the
Clip menu, and select
Change image/color duration .
To make a slide-show video, do as you've done, drop your images into the time-line. Next you will probably want to think about using pan/zoom effects, known as the
Ken Burns effect. This is found on the
Image tab beneath the Resampling option. These can be keyframe customized to suit your needs.
Then you may want to use some transitions between your images. I've always favored the Cross-Fade, unless I'm needing something different to help with the mood of the video, or particular point in the video. Transitions are found in the Effect step, the default Effect library is set to Film. Click on the down-arrow to open the drop-down menu for more categories, Cross-fade is found in the FX category.
Subtitles are sometimes used to give the viewer more information on the image they are viewing, like the location, or date. Just go to the title step to add any titles. Then maybe some background music, or narration.
You can see along the top, that VS is setup to follow Steps, just proceed along those steps in building your video. The last being the
Share step. This is where you render of course.
Now if you're wanting to put your masterpiece onto DVDs. then you would select Share>Create video file> NTSC (or PAL) DVD. This will provide you with a DVD compliant MPEG-2 video file. Once the video file is created, you can view it using a software video player. Then to produce your DVD, if you have not already closed VS, select File>New Project, and go directly to the
Share step, and select
Create Disc, which will open the Burn module.
In the Burn module, you insert your video file that you just created, and continue to build your menu, add chapters, then finally burn the DVD, or Create DVD Folders, or an ISO file. Creating DVD Folders before actually burning a DVD, allows you to again preview your work, making sure everything is the way you want it. If not you can go back and make changes, without having wasted a disc.