My Prusa Mendel finally worked fine and made me happy after some printing issues were corrected. Now the small prints of my proyect look very good, so I decided to go for the biggest part of it which is completely flat and its dimensions are 7" by 4 1/2". Aprox the 75% of the layer was printed very good, but some spreaded excess of PLA started to build up on that first layer.. The extruder was at 190 grades and the bed at 80. I used the fan at 50% all the way until I decided to stop it. I would gladly appreciate if you guys have an idea of what is happening and give me some advise. Attached is pic of that first layer.

Unfortunately can not attach a pic in this forum. Do not understand the reason.

Regarding attaching pictures - make sure you resize them down so that they're not over the limit (which is around 600K IIUC).
It would be really helpful to see your problem.

Sometime the first layer is a bit bigger because the slicing software is configured to extrude more plastic initially to get better adhesion to the bed. As an experiment, you can try printing with a raft, and see if the problem is now with the raft layers, and not the model layers.