There are types of conditional sentences:
The first instance is also the easiest
if (something happens in present or future tense), then (something will happen in present or future tense)
si + condition phrase in simple present or future tense, + phrase of consequence in simple or present tense
for example:
if i finish my homework early, i will go to the party
si termino la tarea temprano, iré a la fiesta.
If I eat less, I lose weight
si yo como menos, adelgazo.
The second situation is hypothetical
if (general hypothetical condition), (hypothetical result): this situation is not specific to time
For example,
If I had more money, I would buy a new house
I would appreciate it if you could help me
si (condition written in imperfect subjunctive), (consequence written in conditional)
Translation of examples above:
si tuviera más dinero, compraría una casa nueva
Apreciaría si me pudiera ayudado
The third situation
if (hypothetical condition specific to a situation in the past), then (possible consequence)
For example:
if you had told me, i would have gone
si (condition written in past perfect subjunctive (with hubiera)), (the possible consequence written in past perfect in the indicative form (with había))
Translation of the example above:
Si me lo hubieras dicho, yo habría ido.