I try to bake baguette. But my oven just on bottom element on bake position. Is that reason why I ruined my baguettes? Please advise me the right way to baking bread.
Since you mention your oven has only a bottom heating element and you have ruined baguettes when baking them, I'll take a guess that your problem is that the bottoms of the loaves are too dark, but also suggest some general baguette baking guidelines.
First, if the bottoms of your loaves are in fact too dark, bake them in a higher position in the oven, moving the baking rack if necessary.
A baking temperature of 400F/200C works well; heated fully before inserting the bread.
The oven should be steamy for the first 15 minutes or so of baking. If your oven does not have steam injectors, this can be accomplished by adding 1/2 cup or 150ml of water into the oven (I generally just splash it on the bottom after sliding in the bread) then opening the door for 30 seconds after about 15 minutes.
A baking stone (or improvised alternative such as bricks) that has been pre-heated and onto which the baking pan is placed, will help keep the heat more even, however I've found this to affect the results only very slightly.
Please provide more details about how the baguette has been ruined and we may be able to give you a better answer.