How can I stake tomato limbs after they have been growing on the ground and heavy? I have most of the plant in a cage but some escaped and when I try to put it in the cage, it breaks. I am a new gardener!
An already established plant is often set in its ways and the old growth is best left alone. However the new growth is soft and amenable to new training. Figure out a suitable support based on the new growth, even if it is only a stiff stake pushed into the ground at each growing point and tie in/train new growth up the stake to keep it off the ground. The old stuff can stay where it is; make the best of any fruit down there, maybe on a bed of straw, harvest early to avoid slug damage and allow the old stems to root along their length. This will strengthen the new growth and enhance the possibility of new clean fruit to come.
Without a picture it is difficult to advise.
You need to tie the vines to the cage.
Below are some images of vine ties. I am not recommending these products they are to give you an idea. You can use twine or thin rope also.
For more ideas watch some videos on the topic: YouTube "Tomato ties" search
You can use a combination of ties and string. Put a tie around the vine then tie the string to the tie. Then tie other end of the string to the cage (or anything above the plant). A strip of cloth (1-2" x 8-12") can be used as a sling in place of a tie for heavier vines.
I do not use a cage. I just tie the vine to a stake.
I use furring strips for a stake: Furring Strip