Welcome to the forum Tom.
It sounds like you just need to chain the frames together.
The red cross in a box shows that there is text that Scribus can't currently display, because it's got nowhere to display it.
Go to menu "View -> Show Text Chain". This will show you, by way of a set of arrows from frame to frame, which frames are chained so that the text flows from one to another.
If you want the text to flow from one frame to the next then click on the frame you want the text to flow from, then press the Link Text Frames icon (two tall rectangles with a green arrow) or press N, then click on the frame you want the text to flow into. Continue this way until all of your text flows nicely.